J/AJ/135/966 Circumstellar disk evolution in NGC 2068/71 (Flaherty+, 2008)
Evidence for early circumstellar disk evolution in NGC 2068/71.
Flaherty K.M., Muzerolle J.
<Astron. J., 135, 966-983 (2008)>
=2008AJ....135..966F 2008AJ....135..966F
ADC_Keywords: Accretion ; YSOs ; Spectroscopy ; Photometry, infrared ;
Photometry, SDSS ; Extinction ; Radial velocities ;
Rotational velocities
Keywords: circumstellar matter - ISM: individual (NGC 2068, NGC 2071) -
planetary systems: protoplanetary disks - stars: formation -
stars: pre-main sequence
Abstract:
We study the disk and accretion properties of young stars in the
NGC 2068 and NGC 2071 clusters. Using low-resolution optical spectra,
we define a membership sample and determine an age for the region of
∼2Myr. Using high-resolution spectra of the Hα line we study the
accretion activity of these likely members and also examine the disk
properties of the likely members using IRAC and MIPS mid-infrared
photometry. A substantial fraction (79%) of the 67 members have an
infrared excess while all of the stars with significant infrared
excess show evidence for active accretion. We find three populations
of evolved disks (IRAC weak, MIPS weak, and transition disks) all of
which show decreased accretion activity in addition to the evidence
for evolution in the dust disk.
Description:
Low-resolution optical spectra were taken with the Hectospec
instrument on the MMT (Multiple Mirror Telescope, Mount Hopkins, USA),
in 2004 November 5 and 2005 October 23. High-resolution optical
spectra were taken with the Hectochelle instrument on the MMT. Two
fields, each with an exposure time of 3x1200s, were observed on 2004
December 3, 2005 and November 14. Near-infrared JHKs photometry was
taken from the Two Micron All Sky Survey (2MASS, Cat. II/246).
Mid-infrared photometry was obtained using the IRAC and MIPS cameras
aboard the Spitzer Space Telescope. Optical photometry was taken from
the Sloan Digital Sky Survey (SDSS, Cat. II/294); the Orion field was
observed as part of an early calibration run through the Galactic
plane in the fall of 1998 and the fall of 1999.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 119 69 Photometry of likely members
table2.dat 63 69 Cluster members identified from low-resolution
spectra
table3.dat 61 67 Stellar parameters for likely members
table4.dat 50 34 High-resolution spectra of likely members
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
J/AJ/129/907 : New Ori OB1 members (Briceno+, 2005)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- [FM2008] Object identification number
6- 11 F6.3 mag gmag ? SDSS g band magnitude (1)
13- 18 F6.3 mag rmag ? SDSS r band magnitude (1)
20- 25 F6.3 mag imag ? SDSS i band magnitude(1)
27- 32 F6.3 mag zmag ? SDSS z band magnitude(1)
34- 39 F6.3 mag Jmag 2MASS J band magnitude
41 A1 --- f_Jmag [a] Unresolved source (2)
43- 48 F6.3 mag Hmag 2MASS H band magnitude
50- 55 F6.3 mag Ksmag 2MASS KS band magnitude
57- 62 F6.3 mag 3.6mag Spitzer/IRAC 3.6 micron band magnitude
64- 68 F5.3 mag e_3.6mag Uncertainty in 3.6mag
70- 75 F6.3 mag 4.5mag Spitzer/IRAC 4.5 micron band magnitude
77- 81 F5.3 mag e_4.5mag Uncertainty in 4.5mag
83- 88 F6.3 mag 5.8mag Spitzer/IRAC 5.8 micron band magnitude
90- 94 F5.3 mag e_5.8mag Uncertainty in 5.8mag
96-101 F6.3 mag 8.0mag Spitzer/IRAC 8.0 micron band magnitude
103-107 F5.3 mag e_8.0mag Uncertainty in 8.0mag
109-113 F5.3 mag 24mag ? Spitzer/MIPS 24 micron band magnitude
115-119 F5.3 mag e_24mag ? Uncertainty in 24mag
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Note (1): SDSS u band data is not reported here because of the red
leak in the filter.
Note (2): 'a' indicates that the source is not resolved from a nearby star
in the J band and only an upper limit is reported.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- [FM2008] Object identification
5- 7 A3 --- n_[FM2008] [a-d, ] Individual notes (1)
9- 10 I2 h RAh Hour of right ascension (J2000)
12- 13 I2 min RAm Minute of right ascension (J2000)
15- 19 F5.2 s RAs Second of right ascension (J2000)
21 A1 --- DE- Declination sign (J2000)
22- 23 I2 deg DEd Degree of declination (J2000)
25- 26 I2 arcmin DEm Arcminute of declination (J2000)
28- 32 F5.2 arcsec DEs Arcsecond of declination (J2000)
34- 38 A5 --- SpR Spectral type range
39 A1 --- f_SpR [c] indicates continuum stars (2)
41- 44 A4 --- SpT ?=- Spectral type adopted
46- 50 F5.1 0.1nm EWHa Hα equivalent width
52 A1 --- l_EWLi Limit flag on EWLi
53- 57 F5.2 0.1nm EWLi Lithium equivalent width
59- 63 A5 --- OType T-Tauri type (CTTS or WTTS)
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Note (1): Flag as follows:
a = [OI] 6300Å emission detected in optical spectra.
b = Variable in the optical as observed by Briceno et al. (2005,
Cat. J/AJ/129/907). They measured a spectral type of K6, and Hα
and Li EWs of 98 and 0.4Å respectively.
c = Binary from Padgett et al. (1997ApJ...477..705P 1997ApJ...477..705P).
d = X-ray emission detected by Skinner et al. (2007ApJ...658.1144S 2007ApJ...658.1144S).
Note (2): continuum stars do not show any significant features that could
be used to derive a spectral type.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- [FM2008] Object identification
5 A1 --- f_[FM2008] [a] Possible contamination (1)
7- 11 F5.3 solLum Lum Luminosity (2)
13- 16 I4 K Teff Effective temperature (2)
18- 21 F4.2 solMass Mass Mass
23- 27 F5.3 solRad Rad Radius (3)
29- 31 F3.1 --- Av Extinction
32 A1 --- f_Av [b] no available optical photometry (4)
34 A1 --- l_Acc Limit flag on Acc
35- 39 F5.2 10-8Msun/yr Acc ?=- Accretion rate (5)
40 A1 --- f_Acc [cn] Flag on Acc (6)
42- 46 F5.2 --- alpha Slope of the SED in the IRAC bands (7)
48- 61 A14 --- Disk Disk descriptor (8)
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Note (1): 'a' indicates that the Photometry may be contaminated by
background source with very cool SED, possible a Class 0/I source.
Note (2): The typical uncertainty in effective temperature is 5%, while the
typical uncertainty in luminosity, which includes uncertainty in Teff
and photometric uncertainty, is 10%.
Note (3): derived assuming L=4πR2σT4eff.
Note (4): 'b' indicates that, with no available optical photometry, and
extended emission contaminating the 2MASS photometry, an accurate
extinction could not be derived and we assume a lower limit of 0.
Note (5): If the Hα profile indicates no active accretion then a 0 is
used. If no high-resolution spectrum is available, then no number is
reported.
Note (6): Flag as follows:
c = R-band magnitude from Siess et al. (2000A&A...358..593S 2000A&A...358..593S) 2Myr isochrone
used instead of the observed R-band magnitude to derive the accretion
rate from veiling.
n = no stand.
Note (7): SED slope, α, from a least-squares fit of a power-law
(λ.Fλ∝λα) of the four IRAC
bands for each star
Note (8): Disk descriptors as follows:
Strong = (αIRAC>-1.6,[8.0]-[24]>2.4),
MIPS-weak = (αIRAC←1.6,[8.0]-[24]<2.4),
IRAC weak = (-1.6>αIRAC>-2.5),
Gap = small short wavelength excess, large [24] excess,
No = no disk (αIRAC←2.5).
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- [FM2008] Object identification number
5 A1 --- f_[FM2008] [b] P Cygni profile (1)
7- 10 F4.1 km/s RV ?=- Radial velocity
12- 14 F3.1 km/s e_RV ? Radial velocity uncertainty
16 A1 --- l_vsini Limit flag on vsini
17- 20 F4.1 km/s vsini ?=- Rotational velocity
22- 25 F4.1 --- R ?=- Tonry & Davis (1979AJ.....84.1511T 1979AJ.....84.1511T)
R value (2)
27- 29 I3 km/s HaFW1 Hα full width 10%, 1st measure
31- 33 I3 km/s HaFW2 ? Hα full width 10%, 2nd measure
35- 39 F5.1 0.1nm HaEW1 Hα equivalent width, 1st measure
41- 44 F4.1 0.1nm HaEW2 ? Hα equivalent width, 2nd measure
46 A1 --- l_r Limit flag on r
47- 50 F4.2 --- r ?=- Veiling (r=Fexcess/Fcont) over the
wavelength range of 6490-6501Å
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Note (1): b = Hα profile shows an inverse P Cygni shape indicating
active accretion, despite the small FW 10%.
Note (2): The R value of Tonry & Davis (1979AJ.....84.1511T 1979AJ.....84.1511T). The 90%
confidence interval for vsini is approximately vsini/(1+R).
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 25-Jun-2010